1) Field of the Invention
This invention relates to a so-called viral insecticide which is effective in destroying or controlling injurious insects by using microorganisms pathogenic to them, and to a preparation process thereof.
2) Description of the Prior Art
Viral insecticides adapted to perform bacterial destruction or control of injurious insects by using microorganisms pathogenic to them are attracting interests in recent years, because the microbial insecticides do not give chemical injury to plants and animals. Among such microbial insecticides, certain virus preparations containing nuclear polyhedrosis virus (hereinafter abbreviated as "NPV") as active ingredients have already been put on the market in the United States. The recent state of art of bacterial insecticides was reported for example by Ayusawa, Fujiyoshi, et al. in "Hakko Kogaku", 51, 351-365 (1973). Kamizumi and Katagiri reported separately the utilization of bacterial insecticides in "Hakko Kogaku", 51, 365-374 (1973).
Conventional virus preparations however encounter difficulties in their mass production and have hence poor utility in view of their production costs, since they are each prepared by feeding an artificial feed, which has been added with NPV of a specific host insect, to larvae of the insect so as to infect the NPV to the larvae, allowing both larvae and NPV to multiply as a result of the feeding of the artificial feed, collecting remains of diseased insects, grinding them, and then forming the resultant powder as a preparation.
Since the host range of insect viruses is generally specified to limited species of insects, there is another problem that it is impossible to obtain any single virus preparation capable of showing insecticidal effects against a wide variety of insects.
It is therefore essential to overcome the above-mentioned problems in order to use a virus preparation actually as an agricultural chemical for destroying or controlling injurious insects.